Parse string in Azure Sentinel

[SiddharthRajD]

Hello, we want to parse out the "subscription ID" as a field from the following string. Please let me know how can I do that?

Column Name	string
privateLinkServiceId_	/subscriptions/"SubsriptionID"/resourceGroups/"RG-Name"/providers/Microsoft.Storage/storageAccounts/"Name"

Existing query  ( please suggest what needs to be appended) :

AzureActivity | search "entity"
| extend privateLinkServiceId_ = tostring(parse_json(tostring(parse_json(tostring(parse_json(tostring(parse_json(tostring(parse_json(Properties).requestbody)).properties)).privateLinkServiceConnections))[0].properties)).privateLinkServiceId)

[#2]

@SiddharthRajD 

AzureActivity 
| extend entity_ = tostring(parse_json(Properties).entity)
| where isnotempty(entity_)
| parse entity_ with * '/subscriptions/' subscription_ '/' *
| project subscription_

However SubscriptionId is already a column in that Table, so you can just do 

AzureActivity
| extend entity_ = tostring(parse_json(Properties).entity)
| where isnotempty(entity_)
| project SubscriptionId